hard water

American  

noun

1. water that contains magnesium, calcium, or iron salts and therefore forms a soap lather with difficulty.

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hard water Cultural  

1. Water in which dissolved minerals make it difficult to produce a lather with soap.

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Hard water is usually associated with well water in regions where the rocks contain a large proportion of iron-bearing minerals.

Example Sentences

Other plastics, including ones promoted as highly recyclable, such as clear polyethylene bottles, which hold some medications, or hard water bottles, are being recycled at just 16%.

From Los Angeles Times • Jan. 14, 2026

“It is abrasive enough to get through hard water and works great to polish surfaces. It has to have 0000 at the end,” she cautions.

From Seattle Times • Feb. 16, 2024

Yet stalagmites offer new insights into climate fluctuations because the German researchers could examine the isotopic composition of oxygen in a southern German stalagmite that had been formed from hard water.

From Salon • Jan. 22, 2024

Gordon: The most accurate test for hard water is to send a sample to an accredited independent laboratory.

From Washington Post • Aug. 23, 2022

Stones are hard, water is wet, objects unsupported fall toward the earth’s center.

From "1984" by George Orwell